Device for drying a medium flow

ABSTRACT

The invention relates to a device for drying a medium flow ( 8 ), in particular an air flow, comprising a device housing ( 2 ), in which at least one first and at least one further drying agent ( 4, 6 ) are received, having high moisture absorption capacity in the case of low or high moisture values of the medium flow ( 8 ), and wherein the amount of the respective drying agent ( 4, 6 ) can be selectively set depending on the actual moisture present in the medium flow ( 8 ).

The invention relates to a device for drying a medium flow, in particular an air flow, comprising a device housing in which at least one drying agent is received.

The generic devices are used, in particular, when a container is supplied with an air flow from the outside, and the object is to prevent moisture from infiltrating the container. Such a container can contain, for example, hydraulic oil for supplying a hydraulic system. The infiltration of moisture into the container can lead to a reduction in power or even damage to the attached system. In order to supply an air flow from the outside, the generic devices have an inlet device, so that, for example, when the level of a medium that is introduced into the container drops, air from the outside can be fed into the container by way of the device. The medium in the container can decrease, for example, by removal of the medium. In the reverse case—that is, the level of the medium in the container rises and consequently the air flow must be removed from the container to the exterior—the generic devices often have an outlet device, in addition to the inlet device.

Typically, such drying devices use so-called drying agents, which, however, taken by themselves, are only intended to cover one specific area of a preferred application, in particular, as a function of the moisture situation, temperature, and composition of the medium flow to be dried. Therefore, it is necessary to select from the prior art a drying agent that is the most appropriate for the field of application in order to attain the intended effect.

In this respect, DE 100 31 004 B4 discloses a device for ventilating containers that hold air that has been dried by adsorption. In this case, aluminum oxide is introduced into the container as the adsorbing agent. Then the air is fed from the outside through the adsorbing agent into a container which is to be attached, from which an air removal to the exterior is also possible. The arrangement of a plurality of non-return valves ensures in the solution known from the prior art that the container with the moisture adsorbing agent is charged with air only when the air is actively supplied and not when the air is actively removed. In particular, if the attached container contains hydraulic oil, the efficiency of the adsorbing agent would be reduced if it were traversed by oil vapors of the removed air.

EP 0 135 006 A2 also discloses a device for ventilating with dried air. In this case, a silica gel is the drying agent that is introduced into a container which is supplied with air from the outside by way of a dust filter. After this air has passed through the drying agent, it is fed to a medium conductor, which communicates with the attached container.

Working on the basis of the aforementioned prior art, the object of the present invention is to provide a device for drying a medium flow in such a way that being easy handle, it can be manufactured cost effectively and, in particular, can be adapted in a simple way to a wide range of requirements in the course of drying a medium flow.

This object is achieved with a device for drying a medium flow according to claim 1. Special embodiments of the invention are the subject matter of the independent claims.

The inventive device for drying a medium flow, in particular an air flow, comprises a device housing in which at least a first drying agent is received. Due to the fact that the device housing receives not only at least a first drying agent but also at least another drying agent and that at low or high moisture values of the medium flow at least a first and at least another drying agent exhibit a high moisture adsorption capacity, a plurality of requirements that the drying operation of a medium flow must fulfill in the field can be satisfied in a simple way, in particular, because the amount of the respective drying agent can be selectively set as a function of the actual moisture that is present in the medium flow.

One embodiment of the invention provides that the device housing has a receiving space for receiving at least two drying agents; and that the receiving space has at least one separating device, which can be traversed by the medium flow and which is provided for separating at least two drying agents. This separation of the drying agents by means of a separating device allows, on the one hand, the drying agents that are largely not mixed together to keep their individual properties; and, on the other hand, this separation also allows an individual exchange of the drying agents, especially if one of the two drying agents has weakened significantly in its effect before the other.

One embodiment of the invention provides that a drying agent is a molar sieve—also called a molecular sieve—with a high moisture adsorption capacity at low moisture values of the medium flow; and that at least another drying agent is a silica gel with a high moisture adsorption capacity at high moisture values of the medium flow. Both the molecular sieve and the silica gel are drying agents that have already proved worthwhile in generic devices because of their high efficiency, but are totally different in their individual properties. For example, a molecular sieve has a high moisture adsorption capacity at low relative moisture values of the medium flow, whereas a silica gel has an especially high moisture adsorption capacity at high relative moisture values of the medium flow. By combining at least two drying agents in a device, it is possible to combine the individual properties of the respective drying agents in such a way that the device for drying the medium flow carries out the drying in the most effective way as a function of the actual moisture that is present in the medium flow. In particular, this strategy allows the devices for drying the medium flow to be provided with drying agents in such a way that a high moisture adsorption capacity is guaranteed for the medium flow over as wide a range of the relative moisture values of the medium flow as possible.

One embodiment of the invention provides that at least one separating device can be arranged in a selectable manner in the receiving space and divides in this way the receiving space into at least two receiving volumes for receiving at least two drying agents. Since the receiving volume of the receiving space for the respective drying agents can be influenced by means of the separating device that can be arranged in a selectable manner, the receiving space can be divided in such a way that the division is adapted to one of the intended operating situations, in particular the moisture present in the medium flow, the type of medium flow, the drying agents to be used, etc. Since this division can be performed at the corresponding device—that is, locally—it is possible to use devices which are otherwise identical in design for a wide range of applications, because they can be adapted to the required receiving volumes. Moreover, such a design is also inexpensive, because it is possible to keep a large inventory of drying agents, whereas the volume of the drying agent that has to be introduced individually into the receiving space can be established separately for each individual device.

One embodiment of the invention provides that at least one separating device can be arranged at selectable positions in the direction of the longitudinal extent of the receiving space for dividing the said receiving space. This feature simplifies the division of the receiving space especially in the case of a cylindrical design of the receiving space with a more or less constant cross-sectional area, because the receiving volume of the respective drying agent that can be introduced relative to the total volume of the receiving space can be easily specified as a function of the selected position of a separating device, its relative position to the longitudinal extent of the receiving space. The result is the individual adaptability of the device, since the division of the receiving space can be carried out individually for each device per se as a function of the selected position of the separating device.

One embodiment of the invention provides that at least one separating device is designed in the form of a disk and is provided with passage openings, which can be traversed by the medium flow. The provision of passage openings, which can be traversed by flow, in separating devices that are designed in the form of disks guarantees that a medium flow can flow through at least one separating device; and in this way first a first drying agent and then an additional drying agent can act on the medium flow.

One embodiment of the invention provides that the device housing, being situated on the upstream side of the receiving space, is provided with at least one inlet device for admitting the medium flow into the device housing from outside the device housing, and that at least one inlet device empties into an intermediate chamber, which is arranged outside the receiving space and inside the device housing and which is intended for stabilizing the medium masses. For this purpose, the passage openings can be provided with identical or different sizes; it is also possible to select the arrangement pattern of identical or different passage openings so as to obtain a desired through-flow profile of the separating device that is useful especially for directing the flow as uniformly as possible against a drying agent arranged downstream of the separating device in the direction of flow. In the case of a separating device which is configured in the form of a circular disk, it may be provided for the passage openings that they are defined by radially extending webs and webs that extend in the circumferential direction; and that the size of the passage openings relative to a center of the separating device increases in the radial direction from the interior to the exterior.

One embodiment of the invention provides that a filter device, in particular in the form of a disk-shaped filter foam for distributing the media, is situated between the intermediate chamber for stabilizing the medium masses and the upstream side of the receiving space. In this case, the inlet device can be, in particular, an inlet valve, so that although the medium flow enters via the inlet device into the device housing, it cannot leave the device housing by way of the inlet device. Such a function of the inlet device can be implemented, for example, by means of a non-return valve. The intermediate chambers for stabilizing the air masses also serve to uniformly distribute the medium flow, admitted through the inlet device, in the intermediate chamber, so that the medium flow can exit said chamber in the next phase of the flow route distributed as uniformly as possible over the flow cross-sectional area.

One embodiment of the invention provides that an additional filter device, in particular a filter foam for balancing the packing of the received drying agent, is arranged on the downstream side of the receiving space between it and an end-side closure of the device housing. A filter foam with its non-uniformly distributed pores or more specifically air channels contributes to a uniform distribution of the medium directed against the filter foam, so that this medium leaves the filter foam on the downstream side more or less homogeneously over the flow cross-sectional area. This feature facilitates a uniform flow of the drying agents introduced into the receiving space. Moreover, such a filter device can also serve to hold off the fine dust or other contaminants in the medium admitted into the device. Insofar as a drying agent rests in direct contact against the filter foam on the downstream side, the filter foam also effectively prevents the drying agent or individual small particles thereof from exiting the receiving space into the intermediate chamber for stabilizing the air mass, it being arranged at the upper end of the receiving space and adjacent thereto. Hence, when the receiving space is filled, this filter foam can exert within defined limits a pressure on the poured in drying medium in such a way that even in the course of transporting the device to the site of use, it will essentially retain its position. In particular, it is ensured that the drying agent that is introduced will maintain a constant height relative to the longitudinal extent of the receiving space.

One embodiment of the invention provides that the one filter device and the other filter device can be brought into contact with a sieve plate on the side of said filter device that faces away from the receiving space. This support of the one and the other filter device by a sieve plate and, in particular, on the side that faces away from the receiving space further increases the stability of the filter foams, so that, when installed, the filter foam for distributing the medium is not moved out of its desired position by the drying agent that may be bearing down on it, but rather said filter foam is supported by the sieve plate. Furthermore, the filter foam, which is located at the top in the installed position and which is intended for balancing the packing, is also mechanically supported by the adjacent sieve plate and is moved into close contact with the drying agent received in the receiving space.

One embodiment of the invention provides that a medium conductor, which extends between the sieve plates resting against the one filter device and the other filter device, extends through the receiving space in the direction of the longitudinal extent of the device housing; and that the interior of the medium conductor communicates with a connecting device for connecting the device to a container to be supplied with the dried medium. The dried medium flows via such a medium conductor through the device housing in the direction of its longitudinal extent. In the simplest case, the medium conductor is a piece of pipe that has a cylindrical cross-sectional area and that may optionally be provided on its ends with securing means that simplify its installation in the device housing.

One embodiment of the invention provides that a sleeve-shaped filter element is arranged in the end-side closure of the device housing. In this case, the sleeve-shaped filter element extends in sealing contact between the sieve plate resting against the other filter device and a cap-shaped limiting element of the device housing that is designed as an end-side closure; and its interior communicates with the medium conductor. The sleeve-shaped filter element can be, in particular, an air filter element that has a fineness of approximately 3 μm and that, being upstream of the connecting element as the last filter element in the flow direction, performs a fine filtration of the medium before the medium flows into an attached container. In addition, the sleeve-shaped filter element, against which the flow is directed radially from the outside, also carries out a deflection of the flow direction of the medium flow, because this medium flow enters into the medium conductor when it leaves the sleeve-shaped filter element in the axial direction. The cap-shaped limiting element of the device is a conventional end cap of a filter housing that in the present case closes the device housing in a sealing manner against the environment.

One embodiment of the invention provides that the central region of the separating device, being designed in the form of a circle and resting with its outer wall region against the inner wall of the receiving space, has a recess; and that a flexible edge, formed on the recess and supported on the medium conductor, allows a selective arrangement of the separating device at positions in the direction of the longitudinal extent of the receiving space. The flexible design of the edge of the recess in the separating device makes it possible to secure the separating device at the medium conductor in such a way that it is easy to detach. In particular, such a design allows the separating device to be slid with ease along the medium conductor and, as a result, makes it easy to adapt the receiving volume to the specified boundary conditions.

One embodiment of the invention provides that the device housing is provided with an outlet device outside the receiving space. In this case, a medium flow, issuing from a container attached to the device, can exit the device housing by way of this outlet device to the exterior. In addition, it is possible for a medium flow to enter the device from the container by way of the connecting device. However, the air column forming in the medium conductor of the device causes such an increase in the pressure that an outlet device, in particular a non-return valve, arranged at the bottom in its installed position in the device housing, is opened in time so that the medium issuing from the container is effectively prevented from entering into the receiving space of the device. The use of a non-return valve as the outlet device also effectively prevents the medium, entering from the environment, from being able to enter directly into the medium conductor through the outlet device and then entering into an attached container, because the corresponding non-return valve blocks in this direction.

One embodiment of the invention provides that the molecular sieve content ranges from 10% to 50% and the silica gel content ranges from 90% to 50%; and preferably the molecular sieve content ranges from 25% to 45% and the silica gel content ranges from 75% to 55%; and even more preferred is a molecular sieve content of approximately 40% and a silica gel content of approximately 60% of the total amount of the drying agents introduced into the receiving space. In particular, a combination of approximately 40% molecular sieve and approximately 60% silica gel results in an especially good profile for the moisture adsorption capacity over a wide range of relative moisture values of the medium flow. The advantage of such a combination is that compared to a pure silica gel, such a combination of drying agents yields a significantly higher moisture adsorption capacity at relative moisture values of approximately 5 to 40% of the medium flow.

The invention is explained in detail below by means of an exemplary embodiment shown in the drawings. Referring to the drawings,

FIG. 1 is a highly simplified perspective view of an inventive device that is not drawn to scale and is partially cut;

FIG. 2 shows an enlarged detail of FIG. 1; and

FIG. 3 is a diagram of the adsorption capacity Y of various drying agents as a function of the relative moisture of a medium flow X.

FIG. 1 shows a device for drying a medium flow comprising a device housing 2, in which a first drying agent 4 and an additional drying agent 6 are received. Said drying agent exhibits a high moisture adsorption capacity at low or high moisture values of the medium flow 8. The amount of the respective drying agent 4 or 6 is set selectively as a function of the current moisture present in the medium flow 8.

The center section of the device housing 2 has a receiving space 10 for receiving at least two drying agents 4 and 6. In the drawing according to FIG. 1, a separating device 12, which can be traversed by the medium flow 8 and which is provided for separating at least two drying agents 4 and 6 from each other, is mounted on the edge of the lower third of the receiving space 10.

In this case, it is provided for one of the drying agents 4 or 6 that a molecular sieve having a high moisture adsorption capacity at low moisture values of the medium flow 8, and for the other drying agent 6 or 4 that a silica gel having a high moisture adsorption capacity at high moisture values of the medium flow 8, be introduced into the receiving space 10.

The separating device 12 can be arranged in a selectable manner in the receiving space 10; and the receiving space 10 is divided in this way by the separating device 12 into at least two receiving volumes for receiving at least two drying agents 4, 6. In the drawing according to FIG. 1, a first receiving volume of the receiving space 10 is located underneath the separating device 12; and another receiving volume of the receiving space 10 is located above the separating device 12.

The separating device 12 can be arranged at selectable positions in the direction of the longitudinal extent of the receiving space 10—that is, in the direction of its longitudinal axis 14, which coincides with the longitudinal axis of the device housing 2. This feature makes it possible to divide in a selectable manner the receiving space 10 into at least two receiving volumes. In the drawing according to FIG. 1, approximately one-third of the receiving space 10 is provided for receiving the drying agent 4; and approximately two-thirds of the receiving space 10 is provided for receiving the drying agent 6.

The separating device 12, which is designed in the form of a disk, has passage openings 16, which can be traversed by the medium flow 8. On the upstream side of the receiving space 10, there is at least one inlet device 18 for admitting the medium flow from outside the device housing 2 into the device housing 2. In this case, at least one inlet device 18 empties into an intermediate chamber 20, arranged outside the receiving space 10 and inside the device housing 2. The intermediate chamber 20 serves to stabilize the medium masses of the medium flow 8 flowing in through the inlet device 18. In this context, the medium to be dried can be formed, in particular, by air from the surrounding area of the device.

Between the intermediate chamber 20 and the upstream side of the receiving space 10, there is a first filter device 22, which serves as the filter foam, which is designed in the form of a disk, to distribute the medium of the medium flow 8 flowing out of the intermediate chamber 20. On the downstream side of the receiving space 10, there is an additional filter device 26 that is arranged between said receiving space and an end-side closure 24 of the device housing 2. Designed as the filter foam, this additional filter device serves, in particular, to balance the packing of the drying agents 6 or 4 introduced into the receiving space.

FIG. 1 shows that the one and the additional filter device 22 and 26 can be brought into contact with a sieve plate 44 on the side of the respective filter device that faces away from the receiving space 10. The sieve plates 44 can be provided with passage openings, which can be traversed by the medium flow 8, in a manner analogous to the separating device 12.

A medium conductor 28 extends through the receiving space 10 in the direction of the longitudinal extent of the device housing, in particular extends coaxially to its longitudinal axis 14. When the device is installed in the preferred position shown in FIG. 1, the medium conductor communicates downward with a connecting device 30 for connecting the device to a container (not illustrated) which is to be supplied with dried medium. The medium conductor 28 extends between the sieve plates 44 that rest against one and the other filter device 22 and 26.

The end-side closure 24 of the device housing 2 has a cylindrical filter element 32, which extends in a sealing manner between the sieve plate 44, resting against the additional filter device 26, and a cap-shaped limiting device 34 of the device housing 2 that is formed on the end-side closure 24. The interior of the filter element communicates with the medium conductor 28. In this case, a seal can be inserted so as to ensure a sealing engagement between the filter element 32 and the cap-shaped limiting device 34 of the device housing 2 and/or the filter element 32 and the sieve plate 44, resting against the additional filter device 26.

FIG. 1 shows that a separating device 12 provides a support for the one and the additional filter devices 22 and 26 on their side facing away from the receiving space 10.

It is especially clear from FIG. 2 that the separating device 12 is designed in the form of a circle and, resting with its outer wall region 36 against the inner wall of the receiving space 10, is provided with a recess 38 in its central region. In this case, the recess 38 has an edge, in particular, a flexible edge 40, which, being flexibly supported on the medium conductor 28, allows the separating device 12 to be arranged in a selectable manner at positions in the direction of the longitudinal extent of the receiving space 10.

Outside the receiving space 10, the lower section (as shown in FIG. 1) of the device housing has an outlet device 42, through which a medium flow, issuing from a container (not illustrated) connected to the device, can exit the device housing 2 to the exterior. Such a medium flow would pass through the connecting device 30 counter to the arrow (depicted there) for the medium flow 8 and would not infiltrate the receiving space 10 owing to the air column forming in the medium conductor 28, but rather would exit the device housing by way of the outlet device 42. In this case, the outlet device 42 that can be provided is, in particular, a non-return valve, which effectively suppresses the infiltration of the medium into the device through the outlet device from outside the device, whereas it is possible for the medium flow, issuing from an attached container, to exit by way of the outlet device to the exterior.

FIG. 3 shows the adsorption capacity or water adsorption Y in percent of a molecular sieve 52, a silica gel 54, and a combination 56 of both drying agents 52 and 54 as a function of the relative moisture X in percent of the medium flow. A feature that has proven to be especially advantageous is the use of a combination of 60% silica gel and 40% molecular sieve; the profile of the water adsorption as a function of the relative moisture of this combination of two drying agents is shown by the curve 56 in FIG. 3. In this case, the high water adsorption of the molecular sieve at low relative moisture values is combined with a high water adsorption of silica gel at high relative moisture values of the silica gel. It is very clear from FIG. 3 that, at a relative moisture value of approximately 40%, the water adsorption of the molecular sieve is about the same as the water adsorption of the silica gel; whereas, in the direction of lower relative moisture values, the molecular sieve has a higher water adsorption and, in the direction of higher relative moisture values, the silica gel has higher water adsorption. The relatively steep rise in the water adsorption of the molecular sieve even at very low relative moisture values X causes also the combination of the two drying agents to show, at low relative moisture values, a water adsorption capacity that is higher than that of exclusively silica gel. In determining the water adsorption curves shown in FIG. 3, the tapped density for each of the two drying agents was 700 g/l. 

1. A device for drying a medium flow (8), in particular an air flow, comprising a device housing (2) in which at least a first drying agent and at least another drying agent (4, 6) are received, wherein at low or high moisture values of the medium flow (8) the drying agent exhibits a high moisture adsorption capacity, and wherein the amount of the respective drying agent (4, 6) can be selectively set as a function of the actual moisture that is present in the medium flow (8).
 2. The device according to claim 1, characterized in that the device housing (2) has a receiving space (10) for receiving at least two drying agents (4, 6); and that the receiving space (10) has at least one separating device (12), which can be traversed by the medium flow (8) and which is provided for separating at least two drying agents (4, 6).
 3. The device according to claims 1, characterized in that a drying agent (4) is a molecular sieve with a high moisture adsorption capacity at low moisture values of the medium flow; and that at least another drying agent (6) is a silica gel with a high moisture adsorption capacity at high moisture values of the medium flow (8).
 4. The device according to claim 1, characterized in that at least one separating device (12) can be arranged in a selectable manner in the receiving space (10) and divides in this way the receiving space (10) into at least two receiving volumes for receiving at least two drying agents (4, 6).
 5. The device according to claim 1, characterized in that at least one separating device (12) can be arranged at selectable positions in the direction of the longitudinal extent of the receiving space (10) for dividing said receiving space.
 6. The device according to claim 1, characterized in that at least one separating device (12) is designed in the form of a disk and is provided with passage openings (16), which can be traversed by the medium flow (8).
 7. The device according to claim 1, characterized in that the device housing (2), being situated on the upstream side of the receiving space (10), is provided with at least one inlet device (18) for admitting the medium flow (8) into the device housing (2) from outside the device housing (2), and that at least one inlet device (18) empties into an intermediate chamber (20), which is arranged outside the receiving space (10) and inside the device housing (2) and which is intended for stabilizing the medium masses.
 8. The device according to claim 1, characterized in that a filter device (22), in particular, in the form of disk-shaped filter foam for distributing the media, is situated between the intermediate chamber (20) for stabilizing the medium masses and the upstream side of the receiving space (10).
 9. The device according to claim 1, characterized in that an additional filter device (26), in particular a filter foam for balancing the packing of the received drying agent (6), is arranged on the downstream side of the receiving space (10) between said receiving space and an end-side closure (24) of the device housing (2).
 10. The device according to claim 1, characterized in that the one and the other filter device (22, 26) can be brought into contact with a sieve plate (44) on the side of said filter device that faces away from the receiving space (10).
 11. The device according to claim 1, characterized in that a medium conductor (28), which extends between the sieve plates (44) resting against the one and the other filter device (22, 26), extends through the receiving space (10) in the direction of the longitudinal extent of the device housing (2); and that the interior of the medium conductor (28) communicates with a connecting device (30) for connecting the device to a container to be supplied with dried medium.
 12. The device according to claim 1, characterized in that a sleeve-shaped filter element (32) is arranged in the end-side closure (24) of the device housing (2); and that the sleeve-shaped filter element extends in sealing contact between the sieve plate (44), resting against the other filter device (26), and a cap-shaped limiting element (34) of the device housing (2) that is designed as an end-side closure (24); and its interior communicates with the medium conductor (28).
 13. The device according to claim 1, characterized in that the central region of the separating device (12), being designed in the form of a circle and resting with its outer wall region (36) against the inner wall of the receiving space (10), has a recess (38); and that a flexible edge (40), formed on the recess (38) and supported on the medium conductor (28), allows a selective arrangement of the separating device (12) at positions in the direction of the longitudinal extent of the receiving space (10).
 14. The device according to claim 1, characterized in that the device housing (2) is provided with an outlet device (42) outside the receiving space (10); and that a medium flow, issuing from a container attached to the device, can exit the device housing (2) by way of the outlet device to the exterior.
 15. The device according to claim 1, characterized in that the molecular sieve content ranges from 10% to 50% and the silica gel content ranges from 90% to 50%; and preferably the molecular sieve content ranges from 25% to 45% and the silica gel content ranges from 75% to 55%; and even more preferred is a molecular sieve content of approximately 40% and a silica gel content of approximately 60% of the total amount of the drying agents (4, 6) introduced into the receiving space (10). 